Bruce is our Forum relativity expert. I am not.
However, I have now read it more carfully. I cannot say for sure that it is all correct, for lack of training in relativity. My training is in EM and QM only. But I do have some comments.
***explaining experimental evidence for non-locality in quantum physics, the dark matter issue in cosmology, and the possible unification of forces. ***
The above quote is the only place where he alludes to dark matter, or non-locality and unification for that matter. He makes a strong case that the speed of gravity is essentially instantaneous. But not believing in instantaneity, he says that the gravity speed must be at least 2x10^10 the speed of light. No theory is offered for how this could be true. His argument is purely on experimental grounds. He does imply that physicists have been hood-winking us.
1. Dark matter: Since newtonian theory is used to predict dark matter, in which the speed of gravity is already infinite, I do not see how his arguments for the speed of gravity could change that analysis. Mike's link above also supports the existence of dark matter with no mention of the speed of gravity.
2. Non-locality; He is suggesting that since gravity propagates essential with infinite speed, then that solves the Aspect Exp / entanglement problem, presuming that gravity somehow carries information about the states of the two particles entangled. I think it's unlikely that gravity can carry such info.
3. Unification: Here he may be on to something that I have been talking about for some time. He claims that for causality, particles that travel much faster than the speed of light- almost at infinite speed- are required. There is only one place where such particles are predicted, in 26-D string theory. That theory predicts the existence of tachyons that can travel up to infinite speeds (almost by definition). I do not understand how they calculate that a closed string can move so fast. But the literature is clear that it is so(See the 2 vol. book by Schwarz, Green & Witten). That would suggest that the 26-D unified field is actually the gravitational field.
It follows if so that the 16 compactified dimensions ( that I have associated with Dark Energy) carry the force of gravity instantaneously throughout the universe by keeping all mass particles entangled with each other. So the whole universe acts like one particle as far as gravity is concerned- one huge super medium. Research is then needed to understand compactified dimensions completely.
So I am pleased to find anything that might prompt theoreticians to take a closer look at 26-d string theory ( as opposed to 9, 10, & 11-d superstring theory).